Perhaps it is not hard to deliver ONE powerful punch; perhaps it is not that hard to deliver ONE fast powerful punch too; but it is hard to maintain the same level of power and speed throughout alternate left and right continuous punching.
In the footage there are 3 episodes of Sifu’s demonstrations that will catch your eyes: chi sau at time stamp 00:15-01:03; one-inch punching at time stamp 02:40-03:35; and continuous punching at time stamp 04:35-04:40. It is the third episode we are going to discuss in this post.
The following might be the usual description for delivering a Wing Chun punch: Relax the whole arm, relax and drop the shoulder blade and back muscles onto the elbow towards the front – this will then give out a powerful punch. To make the punch fast, it is then to drop the muscles fast. To make continuous punches fast, nevertheless, you have to drop the left and right muscles fast alternately to send them out, and at the same time “un-drop” the muscles to retrieve the punches back alternately too.
To “un-drop” is to require some muscles to contract or at least to become less active so as to “pull” back the arm. The “drop” and “un-drop” alternate sequence entails the switch between opposite states of the shoulder blade and back muscles. Such muscular switch of states can hardly be close to instant, and thus will gradually fail to catch up the increasing speed intended for the continuous punching. The “drop” and “un-drop” sequence, when forced to be fast, will greatly hamper the impactful power at the full stretch of the punch, as if braking has always been applied well before the punch can reach the end. Usually the stretch will be reduced from its full extent as speed is increasing, shown as a shortened arm reach punching. In the worst case, it will even become a shortened circular punching!
Even if you might have been very skilful in relaxing the shoulders and the back, such that muscles are well maintained not to contract, keeping the resistance to minimum, the speed still can’t be tremendously increased, due to the absence of a leverage that magnifies acceleration into speed (to be discussed soon).
In the third episode, Sifu’s continuous punching well maintains the straight line and to its full extent at impressively high speed, showing no decrease in power throughout.
I suggest that this can be possibly done by the spine oscillating via the rib cage to send the left and right arms (the corresponding shoulder joints then elbow joints then wrist joints) out and back alternately. Hereunder I try to offer an explanation (it is my interpretation only, and the figures used are fictitious just for illustration).
The speed of a joint moving to and fro is dependent on the magnifying factor its preceding joint can offer to it. Take the elbow joint as an example: Say it travels to and fro a distance of 1 foot within 1 time unit. Let’s assume that the 1-foot distance by the elbow represents the punch (i.e. the fist) already achieving its full extent. Now you want to double the speed, i.e. to and fro 1 foot within 0.5 time unit, by just wanting the elbow joint itself directly increasing its own speed. The increase is probably achieved by more intense activity of its neighbouring muscles, mainly the biceps and triceps. All gain in speed is by the elbow itself; little, if not none, magnifying effect is present, i.e. magnifying factor = 1. This will be a demanding task to the elbow.
Alternatively, your focus for increasing the speed is placed on the shoulder joint instead. Muscles in between the shoulder and elbow joints are maintained relaxed throughout; all movement of the elbow joint is fully caused by the shoulder joint rotating from inside. When the shoulder socket is kept stationary (relatively), the shoulder joint rotates the elbow joint to move the 1-foot distance. Now that you aim at moving the shoulder socket itself to and fro, say 3 inches. This extra momentum is added to the original shoulder-joint-rotating to “throw” the elbow joint to and fro the 1-foot distance, but in a shorter duration, counted towards the time needed for the shoulder socket to move the 3 inches (say, it takes 0.5 time unit), not that for the elbow joint to move the 1 foot on its own, as in the previous scenario.
The shoulder socket uses 0.5 time unit to “throw” the elbow joint to and fro the 1-foot distance. So the magnifying factor = 2 (1/0.5).
If you can accept this framework of analysis, let’s proceed.
The same limitation occurs to the shoulder joint: To further increase the speed at the shoulder joint on its own, it probably has to rely on intensifying the activity of its neighbouring muscles, i.e. shoulder blade and chest muscles. The magnifying factor is again just 1, and thus speed can’t be significantly increased. It has to resort to its previous joint in order to obtain a higher magnifying factor. In this case, for the sake of simplicity, the rib cage is regarded as its preceding unit (though not a joint).
The same operation described above applies here. The shoulder blade and chest muscles are kept relaxed throughout, the “rib cage joints” (roughly being where the rib bones joining the spine) as a whole rotates to and fro 1 inch (not much space to rotate there) to cause the shoulder joint to move that 3 inches to and fro but in a shorter duration, say 0.2 time unit. The magnifying factor to the shoulder joint = 2.5 (0.5/0.2). The extra momentum adds to “throw” the shoulder socket to and fro 3 inches which in turn “throws” the elbow joint to and fro 1 foot. The combined magnifying factor to the elbow joint = 5 (2*2.5). Note that the full extent of the punch has not been compromised (represented by the 1-foot distance still travelled by the elbow joint) while the speed is increased 5 times (the combined magnifying factor).
You can carry on arguing in the same way to more preceding joints/units, for example, the pelvis area (represented by the lower centre).
In short, it’s easier to attain and maintain high speed by accelerating within a small distance and oscillating in a small scope inside, and transmitting the speed and thus power to the alternating punches with a multiplying leverage represented by the magnifying factor.
Interestingly, I further suggest, the oscillating rib cage actually bears the same state as in when operating in Biu Jee, except that the elbow is not being navigated back to the upper centre to create a swirling effect (refer to the post Swirling: Active Rib Cage Circling Shoulder Joint Socket for details). As such, to achieve the high speed for continuous punching, a very plausible way is to first open up the rib cage by practising Biu Jee.
A quiz for you: How many punches Sifu delivered in the footage? And within how many seconds?